Pulverizing mill



Jan. 14, 1936.

E. LUNDGREN, 2,027,782

PULVERIZING MILL Filed June 22, 1951 l 4 Sheets-Sheet 1 Jan. 14, 1936. LUNDGREN 2,027,782

PULVERI ZING MILL Filed June 22, 1951 4 Sheets-Sheet 2 aiwgm Jan. 14, 1936. E. LUNDGREN PULVEfiIZING MILL 4 Sheets-Sheet 3 Filed June 22, 1931 NTOR.

1 E. LUNDGREN PULVERIZING MILL Filed June 22, 1931 4 Sheets-Sheet 4 Patented Jan. 14-, 1936 Mi G MILL Eric llnndgren, Linganore Hills, Md.

Application June 22, 1931, Serial No. 545,995

7 lDiaims.

My invention relates to improvements in pulverizing mills for grinding coal and other substances. Forms of apparatus that realize the invention are illustrated in the accompanying 3 drawings which form part of the specifications.

There can be a great variety of arrangements of the essential elements and having this in mind I have shown a number of different forms of apparatus. In said drawings Figure 1 is a cross 9 section along line ll on Figure 2, Figure 2 is a longitudinal section along line 2-2 on Figure 1 and Figure 3 is a longitudinal section along line line 3-3 of Figure 1. Figure 4 is a section along line flt on Figure 3 and Figure 5 is a section along line 5-5 on Figure 3. Figures 6 to 10 inclusive show various forms of the mill. Like reference characters indicate like parts in the several Views.

Reference will first be made to the apparatus illustrated in Figures 1 to 5 inclusive.

The mill has two rollers constituting a set of rollers, one of which rollers of the set is driven by external means so as'to cause it to rotate on its own axis and is designated as driving roller 55 I. The other roller of the set is designated 2, it is a roller similar to roller l and is caused to rotate by being forced against the face of l and is designated as following roller 2. A casing 3 surrounds the roller and has two openings, one which is designated 4 and serves as an inlet for a stream of gaseous fluid, air or gas, and the other of which serves as an outlet for the same stream as well as the finished product of the machine and is designated 5. Deflection vanes 6 and l serve to give the stream a change in direction when they are encountered. A seal plate 8 prevents the gas from passing thru the space shown to the right of roller I. It has a strip of flexible metal or other material, 9, at-

circuiting of the air or gas stream. There are, securely attached to the casing strips of flexible material, designated 55, which serve to prevent the air or gas from passing thru the space formed between the ends of the rollers and the casing and are so arranged as not to interfere with the free movement of the rollers in any direction. A feeder, I0, is arranged to supply the material to be pulverized and is revolvable around a stationary shaft, 13. Feeder I0 is driven by outside means functioning thru some means represented by sprocket it. The speed with which the feeder revolves is controllable so as to regulate the amount of material fed to the mill. The feeder consists of a driving hub, l5, one

tached so as to form a tight seal against short (@l. tit-l2) or more other hubs it and Ill, to which are attached or rigidly secured, a number of strips or blades, is, so as to provide a number of pockets into which the material to be pulverized will lodge or be received and from which it will be discharged when the pockets in their travel around the stationary shaft reach the bottom or lower position. To the right of the feeder is shown a construction providing a duct, it, which is to supply air or gas, preferably but not necessarily preheated, to the feeder pockets. There are a number of openings, 82, connecting the duct to the feeder space. The stationary shaft, it, has a groove in its face, marked it, where the air or gas may make a turn'and leave the feeder by way of one of the pockets which at the time are below the stationary shaft. With certain materials there is a tendency for it to stick in the feeder pockets if moisture is present and the purpose of supplying air or gas, preferably heated, to the pockets is to keep them dry and prevent the material from sticking. It also serves the purpose of aiding in the dislodging of the material as it will form a slight pressure in the smaller end of the pocket and thus forcibly eject the material. The pressure of the air or gas in duct it should be higher than in the space below the feeder. A hearing, 20, supports one end of the shaft of roller l and is so arranged as to prevent the shaft from moving endways, while a bearing, 2|, supports the other end of the same shaft and is so arranged as to permit the shaft a certain amount of endways movement which may be due to expansion of the shaft which in turn may be due to heating or other causes. The bearings, and 2|! are rigidly attached to bed plate or foundation designated 22. There are provided as part of the bearing 20, the upper guides 23 and the lower guides 24, having grooves, 21 and 28 respectively in which are located guide blocks 29 and 30. These guide blocks are provided with holes that receive bushings as it or 32 into which fit the trunnions 33 or 34, rigidly attached to bearing 35. This bearing supports one end of the shaft for roller 2 and is made in such a manner as to prevent the shaft from moving endways in relation to this bearing. The other end of this shaft is supported by bearing 36 which is held against vertical movements by the guides, on the upper side and 26 on the lower. Unlike the arrangements in the guides marked 23 and 26) there are no grooves or guide blocks, but the bearing is free to move endways in the direction of the shaft. The bearing is kept from moving endways in relation to the shaft by the two thrust surfaces, 31 and 38. 39 is one of the two springs which serve to apply pressure to the bearings 35 and 36. The springs react against the follower, 40, which in turn transmits the reaction to the end of screw 4|, which works in a threaded hole in yoke 42. The yokes are attached to the ends'of 23 and 24 which are the guides on one side of the machine and 25 and 26 which are the guides on the other side of the machine. As can be seen this construction confines the forces produced by the springs entirely within the rollers and their shafts, the bearings, guides screw and screw yokes, and does not allow any of these stresses to be transmitted to the bedplate or foundation which will result in a material saving when the machine is being built. The dead weight of roller 2 is prevented from producing a bending moment on the lower guides by the two blocks or supports, 43 and 44 which transmit this weight directly to the bedplate or foundation. The screw, 4|, is locked against turning by a notched wheel 45, rigidly attached to the body of the screw. Into the notches of this wheel fits the locking bar, 46, which is pivoted to the end of the guide or to the screw yoke. There is a square portion, 41, at the end of the screw which is used for turning it by a wrench or other means when an adjustment in spring pressure is being made. The object of the construction involving guides and springs is to allow following roller 2 to move away from driving roller I should an obstruction come between them which can not be disintegrated by the pressure. The purpose is also to allow the rollers to come together after they have become worn. Due to the fact that bearing 35 can turn on its trunnions and bearing 36 can move at right angle or any other angle in a horizontal plane, it is possible for the shaft of roller 2 to form any reasonable angle with the shaft of roller I without causing undue stresses on the bearings due to angularity. It is necessary to provide enough clearance around the shaft of roller 2 to allow it to move towards roller I when one or both of the rollers has become worn, and also to move away from roller I when an obstruction enters between the rollers. In order to prevent leakage to or from the machine thru this opening seal plates 48 have been provided. These plates are shown in detail in Figure 5. They fit around the shaft with a fairly snug bore and are forced against ridges 49 on casing 3 by means of springs, four of which ,are shown and designated 50 on Figure 5. These ridges surround the opening provided in the casing for the shaft. This opening is at all times covered by the seal plate as it has enough length to cover the opening no matter what the location of the shaft of roller 2 may be. The bore in the seal plate should be large enough to allow for angularity of the shaft and may be further sealed by a ring or washer of some flexible material. The object of the shaft seals is to prevent leakage into the machine when the housing is kept under a pressure less than atmospheric and from the machine when the housing is kept under a pressure higher than atmospheric. Figure 1 shows a chamber designated 5|, in communication with the mill grinding chamber and which serves to receive such heavy objects as will pass between the rollers without being ground and into which they will be carried by the stream of air or gas sweeping past it at high velocity. Such material will be removed from space 5| after cover 52 is detached.

The action of the machine can best be understood from the following description. A pressure differential is created between inlet 4 and outlet 5 by some outside means such as an exhauster, fan, blower, injector or ejector stack or similar device. This pressure differential causes a stream of gas or air to fiow into opening 4 Figure 1. From this point the stream moves in the narrow space between the rollers and the bottom of the housing, at a very high velocity, turning upwards in the narrow space shown to the left of roller 2, still at a high velocity. Above the rollers is a space very much larger than the one below the rollers or to the left of roller 2. This large space causes the air or gas stream to slow down very considerably. In this space the stream also encounters a set of vanes 6 on Figure 1 where it is given a sudden change of direction, to-wit: in a downward direction. After 7 moving further horizontally and transversely towards the right, another set of vanes, I, are encountered and the stream is given another sudden change in direction, to-wit: in a downward direction. From this point the stream moves to;

Wards the outlet, 5, on Figure 1.

The material to be pulverized is placed in hopper located above feeder III on Figure 1 and by its rotation is discharged into the space above the rollers. Here it encounters the gaseous stream previously referred to and which at this point is moving at a velocity suitable for classification. Should any of the material leaving the feeder be of such fineness as is required of the finished product of the machine it will be picked up by the gaseous stream and begin to move towards vanes I, pass thru the turn and leave the machine. Should any material too coarse to be considered finished product be picked up from the feeder discharge it will be precipitated by vanes I, fall on the inclined seal plate, 8, and be returned to the rollers by gravity. The material which leaves the feeder and is too coarse to be picked up by the gaseous stream will fall into the V-shaped space formed by the rollers and by their rotation be carried between them and be greatly reduced in size. The material will be discharged from the rollers at their lower side and fall into the rapidly moving gaseous stream previously described, after which it will be transported by this stream to the larger space above the rollers where the streams velocity will be greatly reduced and where it will also encounter a set of vanes or what may be termed louver openings, marked 6 on Figure 1. Here there will also be a sudden change in direction and the coarser particles discharged from the rollers will be thrown out of the stream due to their inability to make the turn under the influence of the centrifugal force. The fine and medium fine parti cles will move with the gaseous stream towards the right where vanes or louvers I, will be encountered and the medium fine particles thrown out as previously described. The gaseous stream will now leave the machine, carrying with it such fine particles as can be considered finished product of pulverized material. The gaseous fluid which has been used as a vehicle for the material thru and from the machine can be returned to the machine after all or part of the material has been separated from it by means of a cyclone or other form of separator, or a continuously renewed supply of gaseous material may be pro vided.

- trative embodiment,

It is a well known fact that rollers working under conditions as described above have a tendency to wear more in the center than at the two ends. For this reason a set of deflector plates, designated as 53 on Figures 1 and 2, have been provided and which may be so adjusted that a portion of the material which would normally leave the feeder and be deposited in the center of the rollers, will be deflected towards the ends where the wear will be proportionately increased. This equalization of wear is carried a step further as means are provided to shade a portion or portions of the feeder so that a smaller amount of material will be fed above such portions of the rollers where the heaviest wear is to be found. These means are designated as 54 on Figure 2. They consist of strips or segments of metal or other material movably fastened above the feeder.

While for purposes of illustration a certain embodiment of the invention has here been described in detail, there can, as previously mentioned, be a great number of variations in the arrangements of the elements involved and several modified forms will now be referred to. Each of these however functions in general according to the features described in connection with the mill of Figures 1 to 5.

Figure 6. This shows the mill with two horizontal rollers in vertical arrangement.

Figure 7. This shows a mill identically as described in the illustrative embodiment, but for purposes of obtaining greater capacity a plurality sets of rollers is employed. The gaseous stream picks up the finished product from the upper set of rollers before it reaches the lower set or sets, while the coarse material is deposited upon the lower rollers and is reground. The material discharged from the lowerset will be carriedto the space above these rollers where there will be a reduction in velocity of the stream due to a larger area of the passage and a certain amount of coarse material will be deposited here and be reground without having to be returned to the classifier chamber located above the upper set of rollers. It is also possible to install vanes or louvers in the space between the two sets of rollers and in this case the machine would be in substance two machines as described in the illusplaced one above the other and working in series with each other. Each set of rollers may be driven from a separate source of power or from the same source of power by means of any kind of 'a drive or gearing.

Figure 8. This shows a mill having three rollers, of which one is driver by outside means, the others being driven from this roller by friction. The material entering as described in the illustrative embodiment, between the two upper rollers and is, when discharged from these, sent between the middle and the lower rollers. When discharged from the lower rollers the material is carried, by means of the gas stream previously referred to, thru and from the mill as described in the illustrative embodiment. This arrangement may be carried out with any reasonable number of rollers and it is also possible to have more than one roller driven from an outside source should their number be high.

Figure 9. This shows a mill identically as described in the illustrative embodiment, except that the center line drawn between the two rollers forms an angle with the horizontal. There is no difference in action between the two mills.

Figure 10. This shows a mill having three stages of grinding and three stages of air separation. The arrangement is identical to the one described under Figure '7. Any number of stages may be used. The bearing construction for these variations of construction remains essentially the same in all cases allowing the same amount of freedom. of movement for one or more rollers in each set.

I claim:

1. A pulverizing mill having a casing within which there is located at least one set of pulverizing rollers that comprises a driving roller and a following roller, each of which rollers is cylindrical and rotates about a horizontally and longitudinally extending axis thereof, means for driving the driving roller and means for downwardly feeding the material to be pulverized to the bite between said set of rollers so that the material passes downwardly between the rollers of said set whereby the rolled or crushed material is discharged from the rollers in a downward direction, said casing having an air inlet opening at the lower portion thereof and an air discharge opening at the upper portion thereof and which casing is constructed and arranged with respect to the rollers so that an air passageway or conduit is provided, below the rollers, that leads to an upwardly extending passage or conduit provided between the face of one of the rollers and an upwardly extending section of the casing, and which last mentioned conduit leads into a relatively large separating out space or chamber provided above the rollers, which conduits are arranged and proportioned so that air passing inwardly through the air inlet opening flows in a relatively rapidly moving stream through the channel provided below the rollers whereby the material discharged by the rollers can drop downwardly into the rapidly moving rating out space whereat the air flow speed diminishes whereby the separating out of heavy material can take place and whereby the separated out material can drop back into the rollers for repeated operation thereupon, the arrangement of the air flow being such that the air which passes into, forwardly through and finally outwardly from the separating out chamber through the outlet opening of the casing must pass through the material to be crushed as it passes from the feeding means to the rollers.

2. A pulverizing mill having a casing and therein a plurality of sets of crushing and pulverizing rollers, each set having a plurality of rollers the axes of which extend horizontally and longitudinally and of which one roller in each set has means exterior of the casing for rotating the same while the other rollers of the sets are follower rollers, the mill casing being arranged with respect to the rollers therein and constructed so that it provides a small receiving chamber below the rollers, a larger separating out chamber above the rollers and a conduit leading from the small receiving chamber upwardly past a curved crushing face of one of the rollers to and into the larger separating out space or chamber, and means for feeding and passing the material downwardly to the rollers, the casing being provided with an inlet opening leading to the receiving chamber or space below outlet opening leading from the separating out space above the rollers, and because of which the rollers and with an inlet and outlet openings a stream of gaseous fluid may enter the inlet opening and flow transversely through the receiving chamber or space which is below the rollers, thence with crushed or pulverized material entrained therein upwardly to and into the separating out space above the rollers, thence transversely through the separating out chamber or space and finally therefrom through the outlet opening, said separating out chamber having therein horizontally and longitudinally extending deflecting vanes arranged in transversely spaced vertical sets and which are relied upon to cause the stream to make sudden turns so as to precipitate such particles entrained in the stream which are too large to be considered as final product of the machine and for thereby causing such particles to fall and consequently pass back to the receiving space between the rollers with the material to be pulverized, the feeding means being arranged so as to deliver the material to be crushed through an opening in the top of the casing and within the space between the transversely spaced vertical sets of deflecting vanes or blades, said vanes or blades being arranged so that they slope downwardly and forwardly towards said outlet opening.

3. A pulverizing mill which includes in combination, an enclosing casing which when in place provides a structure that is relatively air tight except for an air inlet leading to the forward portion of the lower interior portion of the casing and an outlet leading from a delivery portion of the upper interior portion of the casing, cooperating crushing and pulverizing rollers having cylindrical bodies the longitudinal axes of which extend horizontally, feeding means by which material to be crushed and pulverized is fed into the upper interior portion of the casing and sealing means between the rollers and the casing whereby short circuiting of air is avoided and whereby air which becomes laden with pulverized material is caused to follow a definite path from the lower interior portion of the casing into the upper interior portion of the casing, which said cylindrical roller bodies are arranged within and with respect to the casing so that they in conjunction with said sealing means divide the interior of the casing into a lower interior portion or case that is relatively shallow and restricted into which the rollers deliver the material crushed and pulverized by the rollers and into which inflowing air from the air inlet is received, into an upper interior portion or space that is relatively large to provide a separating out space and from which latter space the outfiowing air laden with crushed pulverized material passfis from the mill through said outlet, and into a defined air flow path leading from said lower or restricted portion or space to said upper interior separating out portion or space, which said defined air flow path comprises a restricted space which is between the rearmost face portion of the body of the set of rollers that deliver the crushed pulverized material into said lower restricted portion or space and a portion of the casing that is at the rear of but which is spacedfrom said rearmost face portion of the roller body; the feeding means being arranged at the top of the casing so that the ma-- terial to be crushed and pulverized is fed and showered into and along the separating out space and in position to drop into the bite of a set of crushing and pulverizing rollers prior to being crushed thereby, the space through which the dropping material thus fed must pass being defined at its longitudinally spaced ends by upright side portions of the casing structure and as to its sides by two sets of transversely spaced louvers provided by plate guide members that are vertically spaced and which are arranged so that the face portions extend forwardly and downwardly in reference to the delivery portion of the upper interior portion of the casing.

4. A pulverizing mill having longitudinally extending horizontal pulverizing elements, a feeder extending essentially the full length of the longitudinally extending horizontal pulverizing elements and located above said elements and a series of longitudinally spaced horizontally and transversely extending deflecting plates located between the feeder and the pulverizing elements and in such a manner that material discharged from said feeder will be deflected from a vertical line and will fall so that a portion of the grinding elements which show heavy wear may be protected and so that the material may be directed in greater abundance upon a portion of the pulverizing elements which show light wear thus equalizing the wear of the pulverizing elements, said mill having a casing within which there is provided a separating out chamber into which the feeder delivers the material and through which the material passes to the pulverizing elements that function within the casing, said mill having within said separating out chamber air current deflecting means constituting part of an air separating out chamber that causes coarse material to pass to the pulverizing elements but that allows pulverized material to be conveyed and passed from the pulverizer because of an air current directed upwardly from below the delivery section of the pulverizer elements through a channel between the end rollers on the one hand and an upwardly extending portion of the casing on the other hand and which said upwardly extending portion of the casing is transversely spaced from the end rollers, and which air current flows past said deflecting means on its way through and from the separating out chamber.

5. A pulverizing mill having an enclosing casing provided with an air inlet opening at the lower portion thereof and an air outlet opening leading from the upper portion thereof, hori zontally extending pulverizing elements provided by cooperating rollers, the axes of which extend horizontally and longitudinally and the operative bodies of which rollers are located within said casing, a plurality of sets of adjustable deflecting vanes provided by longitudinally spaced transversely extending blades or vanes each of which swings about a longitudnally extending axis thereof, feeding means arranged at the top of the casing for directing material to be pulverized in a downward path through the space between said deflecting vanes to position for engagement by the pulverizing elements, the arrangement of the rollers and other associated parts of the pulverizing mill being such that the lowermost face portions of the end rollers are vertically spaced a short distance above the lower interior portion of the casing, such that the rearmost face portion of the end rollers is transversely spaced a short distance from an upwardly extending rear portion of the casing and so that a relatively large space is provided between the uppermost portions of the rollers and the upper interior portion of the casing whereby a restricted receiving space or channel is provided below and at the delivery side of the rollers, whereby a restricted upwardly extending channel is provided at the rear of the end rollers and whereby a large upper separating out space is provided at the upper interior portion of the casing above the rollers, the arrangement being such that the air entering the casing through the inlet opening passes through the channel below and in part defined by the roller elements so as to receive pulverized material delivered from the end rollers of the pulverizing elements and so as to convey the crushed or pulverized material'entrained therein upwardly through the upwardly extending channel and ultimately into the separating out space above the rollers thence through the material dropping to the rollers and so that the air with the fine particles therein ultimately passes outwardly to and through said outlet opening.

6. A pulverizing mill having a casing, horizontally extending pulverizing elements provided by cooperating rollers the axes of which extend" horizontally and longitudinally, feeding means provided at the top of the casing and constructed for delivering material'to the pulverizing elements for the full length thereof, horizontally and transversely extending shafts below the feeding means and carrying deflecting vanes provided by longitudinally spaced transversely extending plates arranged for directing at will material in larger quantities to certain portions of the rollers than to others and to thereby regulate the wear upon the rollers, and above the rollers but below the feeding means two sets of longitudinally extending deflecting plates be- 5 tween which sets thetransversely extending defiecti'ng plates are located, which said sets are sufliciently spaced to define a downwardly extending passageway through which the material fed by said feeding means must pass on its way to the rollers, each said set of longitudinally extendingdefiecting plates being composed of vertioally spaced plates that slope forwardly and downwardly, there being one set of such plates over one roller of a pair of the cooperating rollers and another set of such plates over the other roller of said pair of cooperating rollers.

'7. A pulverizing mill having the features of construction as defined in and by the claim last preceding and according to which there is also included a sealing plate that is located at the forward side of the foremost set of longitudinally extending deflecting plates and which seal-- ing plate extends downwardly and rearwardly towards but terminates immediately above the roller of the pair of rollers which is below the foremost set of said deflecting plates.

rare LUNDGREN. 

